Heat-responsive material



Patented Nov. 27, 1928. I 1,693,369

warren .s'raras PATENT OFFICE.

PAUL B. COCHRAN, OF WILKINSBURG, PENNSYLVANIA, ASSIGNQR TO WESTINGHOUSEELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.'

, HEAT-BESPONSIVE MATERIAL.

No Drawing. Application filed April 21, 1927.' Serial No. 185,665.

My invention relates to compositions of on Whether a liquid or'a plasticcompound 55 matter and-particularly to compositions that is desired. Forthe purpose of making a are responsive to temperature changes. paint, aconvenient mixture is twenty-five It is among the objects of myinvention to parts of the prepared pigment and seventyprovide a materialthat Will indicate the five parts of the vehicle.

changes in temperature when it is heated The pigment is prepared bythoroughly and will return to its original color when mixing cuprousiodide and mercuric iodide cooled. with or Without the addition of aninert ma- Another object of my invent-ion is to proterial. The iodidesalts may be mixed con- 10 vide a heat-responsive material that is wa--veniently by grinding them together for one terproof and that willWithstand weatherto four hours in a ball-mill or in an edgeing. runner.When thoroughly mixed and Hitherto it was known that the double ground,the pigment is an extremely fine iodide of mercury and copper wouldchange powder, ready to be incorporated in the vecolor when it washeated and water-soluble hicle.

coating compositions containing the com- For the vehicle, I prefer anoil varnish pounds of mercury and copper were sugcontaining no drier,although the drier may gested. The water-soluble compositions beincluded in the varnish, if desired. Other change from thecharacteristic bright red transparent vehicles such as shellac orlaccolor of the double iodide to a darker color quer may be used for thevehicle provided or to a brown color at about 87 (1- it is transparent.The term lacquer is in- 75 Such compositions, particularly when in:tended to include lacquers of the cellulose the form of a paint, wereuseful formany ester type. The pigment may be incorpo-' purposes, butWhere they were exposed to rated in still other vehicles such as trans-Weathering, or to oil, the soluble material parent resins or in plasticmaterials, such was not sufliciently permanent. Furtheras celluloid. 780 more, the usefulness of the material was When the material is madeinto a paint, limited by its rather high transformation it is bright redin color and has oo'd covertemperature. ing qualities, and when the founation upon My invention provides a materialthat will which thecomposition is spread is heated change color at about C. The low tem toabout 65, the paint loses its bright red perature at which thetransformation point color and takes on a brown tint. occurs makes mynew material useful, for ex- Although I have described the specific emample, as a safety device when it is in the bodiment of my invention, Ido not wish to 35 form of a paint for coverin the whole or be limitedthereto as modifications of my portions of apparatus whic operate bestinvention will suggest temselves to those at comparatively lowtemperatures. or apskilled in the art without departing from paratus inwhich liquids having a low boi the spirit of my invention as defined inthe ing point are to be processed. Another use annexed claims. 7

40 of the material is for covering parts of ma- I claim as my invention:

chinery that are likely to become heated in 1. A heat-responsivematerial comprising order to indicate when it is being operated avehicle and a composition including about at an unsafe temperature.thirty parts cuprous iodide and about seventy My paint consists of apigment comprisparts mercuric iodide. 45 ing a composition of cuprouslodide and mer- 2. A heat-responslve materlal comprising curic iodideand a lacquer or varnish vehiawaterproof vehicle and a compositionincle. Although the proportions of the coneluding about thirty parts.cuprous iodide. stituents of the pigment may be varied and and aboutseventy parts mercuric iodide. other inert material may be incorporatedin 3. A heat-responsive materialcomprising 50 the pigment, I prefer tocombine the cuprous a liquid waterproof vehicle and a compos1- iodideand mercuric iodide in the proportions tion including about-thirty partscuprous of 30% cuprous iodide to 70% mercuric iodide and about seventyparts mercuric iodide. The amount of vehicle used may also iodide. bevaried within broad limits depending up- 4:. A heat-responsve materialcomprlsmg an oil varnish having incorporated therewith a compositionincluding about thirty parts cuprous iodide and about seventy partsmercuric iodide.

5. The method of making a heat-responsive material which comprisesgrinding about thirty parts cuprous iodide and about seventy partsmercuric iodide to form a powder and then incorporating said powder in awaterproof vehicle.

6. The method of making a heat-responsive paint which comprises grindingabout thirty parts cuprous iodide and about seventy parts mercuriciodide to form a powder and then mixing the pigment thus formed with anoil varnish.

7. The method of making a heat-responsive paint which comprises grindingabout thirty parts cuprous iodide and about seventy parts mercuriciodide thoroughly together to form a powder and then mixing the pigmentthus formed with a vehicle in the proportion of about twenty-five partsof the pigment to about se enty-five parts of the vehicle.

In testimony whereof, I have hereunto subscribed my name this 19th dayof A ril, 1927.

PAUL B. COG BAN.

